3,654 research outputs found
Holographic Reduced Representations for Oscillator Recall: A Model of Phonological Production
This paper describes a new computational
model of phonological production, Holographic
Reduced Representations for Oscillator Recall, or HORROR. HORROR's
architecture accounts
for phonological speech error patterns by combining
the hierarchical oscillating context signal of the OSCAR serial-order
model~\cite{VousdenEtAl:2000,BrownEtAl:2000} with a holographic associative
memory~\cite{Plate:1995}.
The resulting model is novel in a number of
ways.
Most importantly, all of the noise needed to generate errors is intrinsic
to the system, instead of being generated by an external process. The
model features
fully-distributed hierarchical phoneme
representations and a single distributed associative memory.
Using
fewer parameters and a more parsimonious design than OSCAR, HORROR accounts
for error type proportions, the syllable-position constraint, and other
constraints seen in the human speech error data
Fractional Quantum Hall Effect via Holography: Chern-Simons, Edge States, and Hierarchy
We present three holographic constructions of fractional quantum Hall effect
(FQHE) via string theory. The first model studies edge states in FQHE using
supersymmetric domain walls in N=6 Chern-Simons theory. We show that D4-branes
wrapped on CP^1 or D8-branes wrapped on CP^3 create edge states that shift the
rank or the level of the gauge group, respectively. These holographic edge
states correctly reproduce the Hall conductivity. The second model presents a
holographic dual to the pure U(N)_k (Yang-Mills-)Chern-Simons theory based on a
D3-D7 system. Its holography is equivalent to the level-rank duality, which
enables us to compute the Hall conductivity and the topological entanglement
entropy. The third model introduces the first string theory embedding of
hierarchical FQHEs, using IIA string on C^2/Z_n.Comment: 36 pages, 6 figures; v2: with an improved derivation of Hall
conductivity in section 3.2, typo corrections, and additional references; v3:
explanations and comments adde
Massive MIMO is a Reality -- What is Next? Five Promising Research Directions for Antenna Arrays
Massive MIMO (multiple-input multiple-output) is no longer a "wild" or
"promising" concept for future cellular networks - in 2018 it became a reality.
Base stations (BSs) with 64 fully digital transceiver chains were commercially
deployed in several countries, the key ingredients of Massive MIMO have made it
into the 5G standard, the signal processing methods required to achieve
unprecedented spectral efficiency have been developed, and the limitation due
to pilot contamination has been resolved. Even the development of fully digital
Massive MIMO arrays for mmWave frequencies - once viewed prohibitively
complicated and costly - is well underway. In a few years, Massive MIMO with
fully digital transceivers will be a mainstream feature at both sub-6 GHz and
mmWave frequencies. In this paper, we explain how the first chapter of the
Massive MIMO research saga has come to an end, while the story has just begun.
The coming wide-scale deployment of BSs with massive antenna arrays opens the
door to a brand new world where spatial processing capabilities are
omnipresent. In addition to mobile broadband services, the antennas can be used
for other communication applications, such as low-power machine-type or
ultra-reliable communications, as well as non-communication applications such
as radar, sensing and positioning. We outline five new Massive MIMO related
research directions: Extremely large aperture arrays, Holographic Massive MIMO,
Six-dimensional positioning, Large-scale MIMO radar, and Intelligent Massive
MIMO.Comment: 20 pages, 9 figures, submitted to Digital Signal Processin
Holographic principle and large scale structure in the universe
A reasonable representation of large scale structure, in a closed universe so
large it's nearly flat, can be developed by extending the holographic principle
and assuming the bits of information describing the distribution of matter
density in the universe remain in thermal equilibrium with the cosmic microwave
background radiation. The analysis identifies three levels of self-similar
large scale structure, corresponding to superclusters, galaxies, and star
clusters, between today's observable universe and stellar systems. The
self-similarity arises because, according to the virial theorem, the average
gravitational potential energy per unit volume in each structural level is the
same and depends only on the gravitational constant. The analysis indicates
stellar systems first formed at z\approx62, consistent with the findings of
Naoz et al, and self-similar large scale structures began to appear at redshift
z\approx4. It outlines general features of development of self-similar large
scale structures at redshift z<4. The analysis is consistent with observations
for angular momentum of large scale structures as a function of mass, and
average speed of substructures within large scale structures. The analysis also
indicates relaxation times for star clusters are generally less than the age of
the universe and relaxation times for more massive structures are greater than
the age of the universe.Comment: Further clarification of assumptions underlying the analysi
New Embedded Representations and Evaluation Protocols for Inferring Transitive Relations
Beyond word embeddings, continuous representations of knowledge graph (KG)
components, such as entities, types and relations, are widely used for entity
mention disambiguation, relation inference and deep question answering. Great
strides have been made in modeling general, asymmetric or antisymmetric KG
relations using Gaussian, holographic, and complex embeddings. None of these
directly enforce transitivity inherent in the is-instance-of and is-subtype-of
relations. A recent proposal, called order embedding (OE), demands that the
vector representing a subtype elementwise dominates the vector representing a
supertype. However, the manner in which such constraints are asserted and
evaluated have some limitations. In this short research note, we make three
contributions specific to representing and inferring transitive relations.
First, we propose and justify a significant improvement to the OE loss
objective. Second, we propose a new representation of types as
hyper-rectangular regions, that generalize and improve on OE. Third, we show
that some current protocols to evaluate transitive relation inference can be
misleading, and offer a sound alternative. Rather than use black-box deep
learning modules off-the-shelf, we develop our training networks using
elementary geometric considerations.Comment: Accepted at SIGIR 201
Stable Clustering Ansatz, Consistency Relations and Gravity Dual of Large-Scale Structure
Gravitational clustering in the nonlinear regime remains poorly understood.
Gravity dual of gravitational clustering has recently been proposed as a means
to study the nonlinear regime. The stable clustering ansatz remains a key
ingredient to our understanding of gravitational clustering in the highly
nonlinear regime. We study certain aspects of violation of the stable
clustering ansatz in the gravity dual of Large Scale Structure (LSS). We extend
the recent studies of gravitational clustering using AdS gravity dual to take
into account possible departure from the stable clustering ansatz and to
arbitrary dimensions. Next, we extend the recently introduced consistency
relations to arbitrary dimensions. We use the consistency relations to test the
commonly used models of gravitational clustering including the halo models and
hierarchical ans\"atze. In particular we establish a tower of consistency
relations for the hierarchical amplitudes: etc. as a
functions of the scaled peculiar velocity . We also study the variants of
popular halo models in this context. In contrast to recent claims, none of
these models, in their simplest incarnation, seem to satisfy the consistency
relations in the soft limit.Comment: 21 pages, 4 figure
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